Trimming  attachment for sewing-machines



(N 0 Model.)

. -T. 0. ROBIN-SON. Trimmjng Attachment for SewingMachi ne's. No.239,983.

Patented April" 12, I881.

Am Mi/M.

.UNITED. STATES PATENT OFFicE.

THOMAS C. ROBINSON,'OF OAMBRIDGEPORT, ASSIGNOR TO CHAS. H. OURRIEB, OFBOSTON, MASSACHUSETTS.

TRIMMING ATTACHMENT FOR SEWING-MACHINES.

SPECIFICATION forming part of Letters Patent No, 239,983, dated April12, 1881.

Application filed April 24, 1880. (No model.)

To all whom it may concern:

Be it known that I, THOMAS UROCKER ROB- INsON, ofGambridgeport,*Middlesex county, State of Massachusetts, have invented anew and Improved Trimming Attachment for Sewing-Machines, for trimmingthe edges of cloth andleather whilein process of sewing, of which thefollowing is a specification.

This invention relates to certain features of construction, which willbe described in the specification, and then pointed out in the claims. r

In the accompanying drawings, Figure 1 is a front View of my deviceattached to a sewing-machine. Fig. 2 is an end view of the same. Fig. 3is a view, from above, of the throat-plate of the sewing-machine asaltered to adapt it to my purpose.

In the drawings only those parts of the sewin g-machine which areessential to the understanding of my device are shown.

In Fig. 1, A is the arm of the sewing-machine. B is the needle-barlever, connected, in practice, in the usual manner, (the oonnection isnot shown in the drawings,) with the needle-bar 0, Figs. 1 and 2, whichit operates.

1), Fig. is'a link formed of a bar or strip of metal attached at itslower end to the needlebar .lever by means of a screw, on which it playsloosely, and projecting perpendicularly upward, and loosely connected bya rivet with the end of lever E, which is called the knifebar lover. Theleft-hand end (in Fig. 1) of the last-named lever is attached by a looserivet to the upper end of a short strip of metal, F, whose lower end isconnected in the same manner to the upper end of a stationary arm, G,which is firmly fixed-to the upper one of the projections forming thehead of the sewingmachine, which are attached to the left-hand end ofthe arm A and support and guide the needle-bar O and .presser-bar G".The knifebar lever E is formed with a collar at or near its middle, thatis provided with a thumb-screw, H, Figs. 1 and 2, which, by screwing in,holds to its place a round rod, J, called the knifebar, that passesthrough the hole in the collar and down through "both of the projectionsfrom the arm A, and bears at its lower end, screwed to its side, a stripof steel, K, Figs. 1 and 2,

called the knife. The lower end of this strip K is sharpened to an edge,thus forming a cuttin g-blade, except a portion of the width of thestrip which is not sharpened, but continued downward a short distance,(say three-eighths of an inch in practice,) and is drawn at the lowerend nearly to a point. I call this portion the lance. This knife K isseen in Fig.2 to be bent to the right diagonally, midway of its length,and then to proceed downward, so that the lower half runs parallel toand close by the side of the needle, at any desirable distancetherefrom, as hereinafter explained. Its cutting-edge works as the upperhalf of a pair of shears, the lower half of the shears being thehardened side of the slot in the throatplate. (Seen in Fig. 3.)

L, Fig. l, is a collar or short cylinder enveloping the knife-bar andheld to it at pleasure by a set-screw, M, Fig. 1. This collar L bears atits lower end a projection toward theleft, as shown in Fig. l, whichprojection carries a small pin, M", projecting perpendicularly downward,and passing into a cylindricalaperture, in which it fits, in the upperprojection of the sewing-machine arm A, and in which it moves loosely.

Fig. 3 shows the needle throat-plate commonly used in sewing-machines.

The view, taken from above, shows the toothed top of the feed device,and to the right of this the aperture for the passage of the needle, andto the right of this a small plate, N,

called the knife-plate, of shape as seen, and held in its place by theset-screw P. The lefthand upper corner of this knife-plate is seen to becut away, leaving a slot between it and the side of the needlethroat-plate. Through the wider portion of this slot passes the lance ofthe knife K, which lance does not quit the slot as the knife moves upand down, and so acts as a guide to the knife and holds it to its directdownward course through the slot.

The operation of the invention is as follows: The sewing-machine beingin the act of sewing, the depression of the needle-bar lever B drawsdown the bar D, and thus the knife-bar lever E, andthe thumb-screw Hbeing tightened-the knife-bar J. The knife K, impinging on the side ofthe slot described in the needle cessity of putting the several productsin the hands of another operator to trim the edges, and guaranteeing apositive uniformity in the distance between the edge of the articleoperated on and the stitch which the sewing.

machine puts into it. It is sometimes desirable to'increase the distancebetween the line of the stitches and the edge of the article operatedon. To do this I first unscrew the screw P, Fig. 3, and press the upperend (in Fig. 3) of the knife-plate N to the right as far as isdesirable, fastening it again, after adjusting my knife K, by screwingup the screw P. 1 then, unscrewing the screws H and M, Figs. 1 and 2,turn the knife-bar J on its own center till the knife Kis at the desireddistance from the needle (not shown) of the sewing'machine. Then,tightening the screws H and M and adjusting and fastening theknife-plate N, I have, as the whole device operates, the distance Idesire between the line of the sewing and the edge of the substanceoperated on.

The knife K, of course, wears away by sharpening; but by means of thecollar bearing it, and the screws H and M, I let the knife-bar J down asrequired, thus compensating for the diminution in length. The specialadvantage of my knife-plate N and its capacity of adjustment is this: Inpractice it is essential, in a machine having the object of this, thatitshould be'possible to increase and diminish the distance of the line ofsewing from the line of the edge of the fabric, as different widths arerequired for different fabrics or different work.

For this purpose it is indispensable, of course, that the slot throughwhich the lance of the knife K (and to a slight distance the edge of theknife itself) passes should have sufficient width to allow the passage.But if the noncutting side of the knife K has not in very closeproximity to it a plate or other object to support the fabric operatedon, the cut-off portion of the fabric would be almost sure to be carrieddown by the downward stroke of the knife, get wedged in between theknife and the side of the plate, and after a few cuts stop the machine,and thus make it practically useless. But with my facility of adjustingmy knife-plate I can place its left-hand edge (in Fig. 1) just so farfromthe line of the downward course of the knife as that the right-handside of the knife will pass the knife-plate, and no more, leaving noroom for the passage of the cut-off portions of the fabric operated on.

I claim- 1. Theadjustableknife-barandknife,incombination with theknife-bar lever E, provided with the collar, the thumb-screw H, thebearing-arm G, the link F, and the link D, adapted to be attached to theneedle-actuating lever, all constructed and arranged substantially asdescribed and shown.

2. The adjustable knife-plate, in combination with the knife, theknife-bar, the collar L and its screw M, the lever E, having the collar,set-screw H, link F, arm G, adapted to be connected with the head of asewing-machine, and the link D, adapted to be connected with theneedle-actuating lever, all constructed and arranged substantially asdescribed and shown.

THOMAS OROOKER ROBINSON.

Witnesses:

LEMUEL P. JENKS, FRED. W. BROWN.

